I mixing hotend with switching y-joiner, is it possible?



  • Hi all,

    Toying with the idea of trying a cyclops+ style mixing hotend, and at the same time use a y-joiner to run filament switching on one of the inputs into the mixing hotend. Is this going to be possible with the duet3d firmware? (I assume so).

    ...Note, this is mainly research at this point. Will be a long time before I can afford.



  • @dmandn said in I mixing hotend with switching y-joiner, is it possible?:

    Hi all,

    Toying with the idea of trying a cyclops+ style mixing hotend, and at the same time use a y-joiner to run filament switching on one of the inputs into the mixing hotend. Is this going to be possible with the duet3d firmware? (I assume so).

    ...Note, this is mainly research at this point. Will be a long time before I can afford.

    As a long term user of mixing hot ends, I can't off had think of a reason why you couldn't do that using Duet hardware and firmware.

    I can think of plenty of reasons why you might not want to do it, but that is an entirely different matter.☺



  • @deckingman
    Would that be due to contamination of colours?

    My idea was to run two colours for mixing (later), with a third filament for supports. However, I am unsure if this would even work without causing blockages.....

    Maybe I should just run with switching and change to mixing only when I am ready to buy those parts...



  • @dmandn Well a Y joiner is just that - you have two filaments going in but only one can come out at any given time. A Y joiner doesn't melt filament therefore it cannot mix filament. It's just a fancy way of loading filament. On the other hand, a mixing hot end does melt filament so the output can be 100% of either of the inputs, or it can be some combination such as 20% of one and 80% of the other.

    Support material cannot usually be mixed with any other material. So when printing support material with a 2 input Cyclops, you would have to feed that into one of the inputs and not use the other input - at least not while the support material is being printed.

    A better approach in my opinion would be to use a 3 input mixing hot end, such as Diamond. You still have the issues that support material will likely need to be printed at a different temperature to the other filaments. So when switching between them, you have to wait for the tool to cool or warm and you have to purge the nozzle of one filament before you can print with the next. But at least all the filaments are loaded and ready for use which is an important consideration when you have to switch filaments on every layer.

    Without going into a lot of detail, both mixing hot ends and multi material "joiners" have their own problems and neither is ideal. Using both together merely means that you have both sets of problems but gain nothing. So my advice would be to either use a single input hot end with some sort of multi material selection device (Y joiner or whatever), or use a multi input mixing hot end, but not both together.



  • I understand that the switching ones don't mix for they do not melt the filament.....I guess running two hotends would get around this but also have their own issues.


  • administrators

    Y-joiners only work (when they work at all) if you can safely retract all the filament from the hot end when it is at printing temperature without causing a jam. That's often possible when using a PTFE-lined hot end, but not with an all-metal hot end.

    One issue I can see with the arrangement you propose is that the Cyclops will need both filaments to be present all the time, to keep the mixing chamber pressurised. Suppose that tools T0 and T1 represent the two inputs to the Y splitter that feeds one of the inputs to the Cyclops, and T2 is the other input to the Cyclops. If you printing using T0 or T2 and then transition to T2, the T0 or T1 filament can remain in place. But when you transition from T2 to to T0 or T1, the firmware has to either do a filament switch or not depending on whether T0 or T1 was in use before T2. The firmware doesn't currently remember that.



  • Then that solves the question and saves me some money....and frustration ☺ Thank you everyone, this plan has been dropped. I will stay with the y joiner until I can justify a micer and then swap to mixing only.


 

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